There are four Army 20-mm guns using similar projectiles and three of these guns use the same cartridge case. The guns using the small size cartridge case are the type 97 anti-tank gun, the Ho 1 (flexible) and Ho 3 (fixed) aircraft guns. The type 98 antiaircraft/anti-tank gun uses the large size cartridge case.

Both cases are made of drawn brass and are of the rimless type. The case is crimped to the projectile by three long crimps and sealed by a clear lacquer.

Propellant: The propellant is graphited smokeless powder made in single perforated cy-lindrical grains approximately 1 1/2 mm in diameter and 3 mm in length. The weight of the propellant in the small case is 35.8 grams and, in the large case, 58.9 grams.

Figure 208 – Type 97 and Type 98 20-mm Ammunition.